Burns And Wound Healing Flashcards
Remarks on smoke inhalation injury
Hydrogen cyanide toxicity may be a component
-tx:
»SODIUM THIOSULFATE: transforms cyanide into a nontoxic thiocyanate derivative, but it works slowly and is not effective for acute therapy
»HYDROXOCOBALAMIN: quickly complexes with cyanide and is excreted by the kidney; recommended for IMMEDIATE THERAPY
»100% oxygen: helps resolve lactic acidosis
Which is a common sequelae of electrical injury
Cataracts
- occur in 5-7% of patients
- frequently bilateral
- typically manifest within 1 -2 eyars of injury
Remarks on silver sulfadiazine
Destroys skin grafts and is contraindicated on burns or donor sites in proximity to newly grafted areas
It may also retard epithelial migration in healing partial thickness wounds
Remarks on mafenide acetate
DOC for burn eschar penetration
Carbonic anyhydrase inhibitor
Remarks on nutrition in burn patients
Baseline metabolic rate increase by as muchh as 200%
Early enteral feeding for px with burns >20%TBSA is safe.
*harris-Benedict equation: gender, age, height, weight; inaccurate in burns <40%
*curreri formula: 25kcal/kg/day + 40 kcal/%TBSA/day
3 days after admission, burn wound biopsy shows 10^4 Pseudomonas organism per gram of tissue. What to do?
Start subeschar clysis with antibiotics
- systemic antibiotics usually are ineffective at this point because by the 3rd day after a burn, blood flow to a burn wound is markedly decreased
- once coloniatiotn of a burn has occurred, surgical excision is EXTREMELY DANGEROUS, as systemic seeding will occur
PE: central vevnous catheter insertion site was red, tender, and warm. What to do?
Removal of central venous catheter, culture tip, and placement of new catheter on contralateral site
Remarks on PMNs and wound healing
First infiltrating cells
Peaks at 24-48 hours
Release proteases such as collagenases, which participate in matrix and ground substance degradation in the early phse of wound healing.
They DO NOT appear to play a role in collagen deposition or acquisition of mechanical wound strength
On the contrary, neutrophil factors have been implicated in delaying the epithelial closure of wounds
The proliferative phase of wound healing occurs how long after injury?
7 days
Roughly spans days 4 through 12
Tissue continuity is reestablished
Strongest chemotactic factor for fibrobalst
Platelet derived growth factor (PDGF)
Stages of wound healing
Hemostasis and inflammation (D0-6)
Proliferation (D4-12)
Maturation and remodeling (D8-6-12months)
Peak of macrophages
48-96 hours
Remarks on T cells
Peak 1 week Post-injury
bridge transition from inflammation to proliferative phase
Final step in establishing tissue integrity
Epithelialization (48 hours)
Remarks on matrix
Earliy matrix: fibronectin and collagen type III
Next matrix: GAGs and proteoglycans
FINAL MATRIX: COLLAGEN TYPE I
Fibrillin
A glycoprotein secreted by fibroblasts
Essential for the formation of elastic fibers found in connective tissue
Over half of the EDS patients manifest genetic defects encoding
alpha chains of collagen type V ✅ (Schwartz)
—> CLASSIC EDS
Classic EDS phenotypic findings
Thin, firable skin with prominent viens Easy bruising Poor wound healing Atrophic scar formation Recurrent hernia Hyperextensible joint
GI problems of EDS
Bleeding
Hiatal hernia
Intestinal diverticula
Rectal prolapse
Vessel problems of EDS
Fragile small blood vessels
Large vessesl may develop aneurysms, varicosities, AV fistulas, spontaneous rupture
Remarks on marfan’s syndrome
Also prone to hernias
Skin may be hyperextensible, but shows NO DELAY in wound healing
When a long bone fracture is repaired by internal fixaion with plates and screws…
Direct bone-to-bone healing occurs without soft callus formation and endochondral ossification (which are characteristic of closed frcture mgt)
HOWEVER, internal reduction does NOT prevent delayed union, eespecially when oinfection or poor blodd supply are present
Impartes the greates tensile strength of GI tract
Submucosal layer, composed of abundant collagenous and elastic fibers
Collagen synthesis in the GI tract is carried out by
Both fibroblasts and smomoth muscle cells
Watertight seal of GI tract is due to
Serosal healing
Steroid-delayed healing of cutaneous wounds can be stimulated to epithelialize by
Topical application of vitamin A
What type of nerve injury involves disruption of axonal continuity with preserved Schwann cell basal lamina
Axonotmesis
3 types of nerve injuries
NEUROPRAXIA (focal demyelination)
AXONOTMESIS (interruption of axonal continuity but preservaitaon of Schwann cell basal lamina)
NEUROTMESIS (complete transection)
Wallerian degeneration
Phagocytes remove the degenerating axons and myelin sheath from the distal stump
The major cause of impaired wound healing is
Local tissue infection
Supplementation of which of the ff micronutrients improves wound healing in patients without micronutriennt deficiency
Vitamin A
- increases lability of lyososomal membranes
- increases influx of macrophages
- directly increases collagen production and epidermal growth factor receptors
- reverse the inhibitory effects of steroids on wound healing
- in the severely injured patient, supplemental doses of vitamin A have been recommended. Doses ranging from 25,000 to 100,00 IU/day have been advocated.
Which type of collagen is most important in wound healing
Type III
Zinc and wound healing
To date, no study has shown improved wound healing with zinc supplementation in patients who are not zinc deficient (2016)
Remarks on cartilage healing
Avascular and depends on diffusion of nutrients across thhe matrix
Additionally, the hypervascular periCHONDRIUM contributes substantially to the nutrition of the crtilage
Signs of malignant transforamtion in a chronic wound include
Overturned wound edges
Treatment of choice for keloids
Excision PLUS adjuvant therapy (e.g. radiation, intralesionsal steroid injection, topical application of silicone sheets)
*excision alone is subject 45-100% recurrence
Remarks on peritoneal adhesions
Occur in 67% of px with prior surgical procedures
Occur in 28% of px with hx of intra-abdominal infection
Following rectal, left colectomy, or total colectomy, SBO 11% within 1 year, and 30% by 10 years
Which growth factor has been formulated and approved for treatment of diabetic foot ulcers?
PDGF-BB
-increases incidence of total healing and decreases healing time
